Figure 1: Schematic diagram illustrating the process of an NS-based WEG. The flow diagram illustrates the preparations, porous hierarchical structure, water-surface interactions, water transportation through channels and generating streaming potential. The center left demonstrates voltage/current generation through evaporation in graphite-NS-graphite sandwich structure. A photograph shows two WS-H+-WEG devices connected in series; two units in series and parallel can power LCD calculator.